The custom home page URL iframe only allows allow-forms/allow-popups/
allow-popups-to-escape-sandbox/allow-scripts, without allow-top-navigation*.
As a result, target="_top" nav/menu links inside the (admin-configured,
trusted) embedded page cannot navigate the top-level window on desktop
browsers, while some mobile browsers still allow it via allow-popups —
causing inconsistent behavior rather than an intended restriction.
Add allow-top-navigation-by-user-activation so user-clicked top-level
links work consistently across devices. This token only permits
user-activated top navigation and does NOT grant same-origin access,
so it avoids the security concern of allow-same-origin.
Co-authored-by: 贺. <kuang@M1.local>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
